forked from mirrors/linux
6716f4d39c
Those who have worked with RCU for some time will naturally think in terms of the long-standing call_rcu() API rather than the much newer call_rcu_hurry() API. But it is call_rcu_hurry() that you should normally pass to synchronize_rcu_mult(). This commit therefore updates the header comment to point this out. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
58 lines
2 KiB
C
58 lines
2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_SCHED_RCUPDATE_WAIT_H
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#define _LINUX_SCHED_RCUPDATE_WAIT_H
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/*
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* RCU synchronization types and methods:
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*/
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#include <linux/rcupdate.h>
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#include <linux/completion.h>
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/*
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* Structure allowing asynchronous waiting on RCU.
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*/
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struct rcu_synchronize {
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struct rcu_head head;
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struct completion completion;
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};
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void wakeme_after_rcu(struct rcu_head *head);
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void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
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struct rcu_synchronize *rs_array);
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#define _wait_rcu_gp(checktiny, ...) \
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do { \
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call_rcu_func_t __crcu_array[] = { __VA_ARGS__ }; \
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struct rcu_synchronize __rs_array[ARRAY_SIZE(__crcu_array)]; \
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__wait_rcu_gp(checktiny, ARRAY_SIZE(__crcu_array), \
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__crcu_array, __rs_array); \
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} while (0)
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#define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__)
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/**
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* synchronize_rcu_mult - Wait concurrently for multiple grace periods
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* @...: List of call_rcu() functions for different grace periods to wait on
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*
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* This macro waits concurrently for multiple types of RCU grace periods.
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* For example, synchronize_rcu_mult(call_rcu, call_rcu_tasks) would wait
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* on concurrent RCU and RCU-tasks grace periods. Waiting on a given SRCU
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* domain requires you to write a wrapper function for that SRCU domain's
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* call_srcu() function, with this wrapper supplying the pointer to the
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* corresponding srcu_struct.
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*
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* Note that call_rcu_hurry() should be used instead of call_rcu()
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* because in kernels built with CONFIG_RCU_LAZY=y the delay between the
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* invocation of call_rcu() and that of the corresponding RCU callback
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* can be multiple seconds.
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*
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* The first argument tells Tiny RCU's _wait_rcu_gp() not to
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* bother waiting for RCU. The reason for this is because anywhere
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* synchronize_rcu_mult() can be called is automatically already a full
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* grace period.
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*/
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#define synchronize_rcu_mult(...) \
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_wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), __VA_ARGS__)
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#endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */
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